Long-term objectives of the research are the explication of the variables of which accommodative hysteresis is a function and to isolate certain visual characteristics of individuals to which accommodative hysteresis may be related. Specific aims include: (1) the relation between the CA/C ratio and the magnitude of accommodative hysteresis; (2) the relation between type of refractive error and magnitude of hysteresis effect; (3) the influence of hysteresis on measures of steady errors of closed-loop accommodation; (4) hysteresis effects as a function of induction-target contrast and spatial frequency; (5) the role of motion perspective in accommodative hysteresis; (6) the early phase of the time course of decay of accommodative hysteresis; (7) a longitudinal study of the relation between susceptibility to accommodative hysteresis and the development of myopia. The primary method entails determining the refractive state of the eye with a laser optometer, modified to make use of the Badal principle, or with an infra red continuous recording optometer. Health related issues arise in connection with the potential role of accommodative hysteresis in clinical refraction and measures of accommodative convergence, accommodative amplitude and range, and in estimates of near and far acuity. Hysteresis effects also may play a role in the etiology of near-work induced myopia.